(Evan Vucci/AP)

Even before Donald Trump became president, people were wondering how long it would be before his behavior became so atrocious or erratic or corrupt that he’d be driven from office. In many ways, Trump has proven to be even worse than we feared. Not only has he not grown and matured, if anything he has become even more infantile and cretinous.

So it isn’t surprising to hear Democrats wonder whether he ought to be impeached, and even talk seriously about it.

But let’s have some straight talk: A Trump impeachment is only a remote possibility, and promoting it now doesn’t do anyone any good. In fact, if Trump is removed before his first term is over, it’s far more likely to happen via the 25th Amendment — in other words, it’ll be Republicans who do the deed.

To be sure, it’s hard to avoid the impeachment question. Yesterday, Democratic mega-donor Tom Steyer sent a letter to party leaders demanding that Democrats running for office pledge to impeach Trump if they take control of Congress. There are also Democrats in the House who want to push for impeachment, but for the moment House Minority Leader Nancy Pelosi (D-Calif.), who thinks it’s a bad idea, is keeping them in check.

You can look at an impeachment pledge as a symbolic act, a way of showing the party base that you’ll fight him to the end. In that sense it would be kind of like the 60 or so times Republicans voted to repeal the Affordable Care Act — it didn’t accomplish anything real, but it was a way of demonstrating their commitment to total opposition. In practical terms, however, nothing Trump has done to this point is going to generate impeachment. Steyer’s bill of particulars amounts to “He’s done a lot of bad stuff,” which is undoubtedly true. But in order to impeach a president successfully, he’ll have to have committed acts that are so clearly high crimes and misdemeanors that even members of his own party think they have no choice but to remove him from office.

And we’re just not there yet, particularly since impeachment would inevitably be saturated in partisanship. If Democrats took the House and voted to impeach Trump, Republicans would immediately close ranks around him, no matter how displeased they are with his performance. There would be zero chance of getting the 67 votes in the Senate required for a conviction, and in the end it would seem to voters like a gigantic waste of time, just as it did when Republicans impeached President Bill Clinton.

To be clear, I’m not saying you can’t make a case that Trump’s misrule is what the Framers had in mind when they wrote impeachment into the Constitution, because you can. Nor am I saying that Trump might not do things in the future — or may have already done things that we haven’t yet discovered — that will be so awful that impeachment will be the only reasonable course. But given the political reality of our age, we’re a ways from that point, and it’s hard to see what is accomplished by demanding that Democrats support impeachment now.

Rep. Al Green (D-Tex.) on Oct. 11 announced his intention to introduce a resolution aiming to impeach President Trump. Green said his resolution argues that Trump "has undermined the integrity of his office with impunity." (C-SPAN)

There is, however, another and perhaps even more likely way that Trump might be removed from office: the 25th Amendment.

There’s been a lot of talk recently about Trump being unfit to hold the office of the presidency, and he absolutely is, by any standard you could devise. His own aides treat him like an unruly toddler who has to be tricked and manipulated into not causing too much damage, an effort that often requires them to go to unusual lengths. On the Iran nuclear deal, for instance, they all agree that it would be insane to pull out of the agreement, which Trump wants to do. So in the face of his rage (“He threw a fit” over it, reports Anne Gearan) they’ve struggled to come up with a policy change that will in effect fool him into thinking he has sort-of canceled the deal, while actually leaving it in place. Other reports quote his own aides and associates describing him as “unstable” and “unraveling,” and explain how aides deal with his impulsive demands by pretending they’ll act on them until, they hope, he forgets what he asked for.

A large portion of his own party understands how erratic and dangerous Trump has become. You’ll notice that when Sen. Bob Corker (R-Tenn.) described the White House as an “adult day care,” his GOP colleagues avoided answering questions about it — but none came forward to say that Corker was wrong.

So it isn’t hard to imagine a scenario in which something dramatic happens, like a crisis that Trump mishandles or a dangerous order he issues that his underlings refuse to carry out, after which the GOP collectively says, “Enough is enough.” According to the 25th Amendment, if the vice president and a majority of the Cabinet declare to Congress “that the President is unable to discharge the powers and duties of his office, the Vice President shall immediately assume the powers and duties of the office as Acting President.”

There’s a somewhat complicated process that would then ensue, with the president having the opportunity to force a congressional vote on his fate. But if the vice president and most of the Cabinet have already taken that dramatic step, chances are it would be a fait accompli. That outcome is more likely than impeachment because it would mean Republicans deciding themselves to remove Trump, which would at least somewhat lessen the feeling that it was a strictly partisan battle.

Here’s the reality Republicans will have to grapple with: If Trump is removed, either through impeachment or the 25th Amendment, it will be a political calamity that will haunt them for years, even decades. Even if some measure of normalcy and order is restored under President Pence — who from my point of view as a liberal would be an awful president, but who at least would be unlikely to start a war because somebody insulted him on Twitter — the GOP would almost certainly suffer terrible electoral defeats in the short term and profound damage to its reputation in the long term. Trump’s status as the worst president in American history would be secured (and yes, he’ll probably get there regardless). Republicans would be hounded and ashamed by their support for him (and yes, they should be anyway). They’d never live it down.

So Republicans would have to decide that’s a price they’re willing to pay in order to remove Trump. If he manages to screw up tax reform for them, they might just do it. But it’s going to take some extraordinary events between now and then, and his fate is going to lie in the hands of his own party. At least until 2020.

As of Oct. 10, the Fact Checker has catalogued 1,318 false or misleading claims by President Trump since he took office in January. (Meg Kelly/The Washington Post)